FIG. 1 is a schematic diagram of a system architecture evolution (SAE) network architecture. As shown in FIG. 1, the SAE network architecture includes: an evolved UMTS terrestrial radio access network (E-UTRAN) that is used for implementing all wireless-related functions of an evolved network and may also be referred to as an E-UTRAN NodeB (eNodeB); a mobility management network element (MME) that is responsible for mobility management of a control plane, including management of a context and a mobility status of a user equipment (UE), allocation of a temporary user identity, and the like; a serving gateway (SGW) that is a user plane anchor between 3GPP access networks and is an interface for terminating a connection to the E-UTRAN; a packet data network gateway (PGW) that is a user plane anchor between a 3GPP access network and a non-3GPP access network and is an interface for terminating a connection to an external packet data network (PDN); a policy and charging rules function entity (PCRF) that is used for policy control and decision and flow based charging control; a home subscriber server (HSS) that is used for storing user subscription information; a UMTS terrestrial radio access network (UTRAN) and a GSM/EDGE radio access network (GERAN) that are used for implementing all wireless-related functions in existing GPRS/UMTS networks, where the UTRAN includes a radio network controller (RNC) network element and a base station (NodeB) network element, and the GERAN includes a base station controller (BSC) network element and a base station (BTS) network element; a serving general packet radio service support node (SGSN) that is used for implementing such functions in GPRS/UMTS networks as routing and forwarding, mobility management, session management, and user information storage; non-3GPP IP access networks (Non-3GPP IP Access) that are mainly some access networks defined by non-3GPP organizations, such as a wireless local area network (WLAN), worldwide interoperability for microwave access network (Wimax), and code division multiple access network (CDMA); and an authentication, authorization and accounting server (AAA Server) that is used for performing access authentication, authorization and accounting functions on a UE.
In the foregoing existing SAE architecture, when a network element is reset due to a fault, a context of a UE stored in the network element is deleted, causing an interruption of an ongoing service of the UE after the network element recovers. To continue with the service, the UE has to re-register with a network and re-initiate the service. More seriously, the UE generally does not perceive the fault in the NE on a network side, and therefore, does not initiate a registration process to re-register with the network and re-initiate the service. Therefore, all services of the UE are actually unavailable.